As the frequencies of electrical equipments have increased, the need to provide assemblies of electrical terminals (such as electrical connectors) at such frequencies has increased. For example, electrical equipments have been able to operate at frequencies in the tens of gigahertz and even higher. It has accordingly been recognized that electrical connectors should be able to operate in such frequency ranges in order to transfer electrical energy at such frequencies to and from such equipment and even to different stages in the equipment.
The electrical connectors generally include at least one electrically conductive terminal or pin for receiving the electrical energy in the operative range of frequencies and a sleeve or body spaced from the terminal for physically and electrically shielding the terminal. An electrical insulator is generally disposed between the terminal and the body and is hermetically sealed to the terminal or body.
Certain materials would be desirable for the terminal or pin and for the shield or body. For example, beryllium copper would be desirable for use as the terminal or pin because it conducts a large current per unit of cross-sectional area with minimal losses in energy. Aluminum would be desirable as the sleeve or body because it is light and is able to provide a good protection to the terminals or pins enveloped by the sleeve. Aluminum is also desirable because its skin anodizes in air and anodized aluminum provides an electrical insulation.
Although the desirable properties of such materials as beryllium copper and aluminum have been known for some time, it has been difficult to provide electrical insulators which will be capable of operating satisfactorily with such materials. This is particularly true when it is desired that the electrical connector have certain properties to make the electrical connector utilitarian. For example, it is often desired that the electrical connector provide an electrical impedance of approximately fifty (50) ohms between its terminals since this is generally the impedance that electrical equipments present to the outside world.
It is also desired that the electrical connector have other properties. For example, it is desired that the electrical connector have a relatively low dielectric constant in order to minimize the distributed capacitances in the connector. These distributed capacitances limit the range of frequencies in which the electrical connector is able to operate. By limiting the operative range of frequencies of the electrical connector, the distributed capacitances limit, as a practical matter, the range of frequencies in which the electrical equipment incorporating the electrical connector is able to operate.
It is also often desired that the electrical connector have other properties. For example, it is desired that the electrical insulator provide a high electrical resistivity through the operative range of frequencies in order to isolate electrically the terminals in the connector from one another and from the sleeve. It is also desired that the electrical insulator provide a flat meniscus so that the electrical insulation in a cable connected to the electrical connector will abut the electrical insulator in the connector. In this way, no air gap will be produced between the electrical insulator in the electrical connector and the electrical insulator in the cable to limit the range of frequencies in which electrical energy can pass effectively between the electrical connector and the cable.
Since it has been known for some time that an electrical connector with the properties discussed above would be desirable, attempts have been made over this period of time to provide an electrical connector with such properties. Since electrical connectors are common components in electrical equipment, such efforts have not been localized. In spite of such attempts, no one has been able to provide an electrical connector with the properties discussed above.